实现模型和投影变换的矩阵
模型变换
只需要处理绕z轴旋转的变换，需要注意输入的角度非弧度。
Eigen::Matrix4f get_model_matrix(float rotation_angle)
{
Eigen::Matrix4f model = Eigen::Matrix4f::Identity();
// TODO: Implement this function
// Create the model matrix for rotating the triangle around the Z axis.
// Then return it.
auto angle = to_radian(rotation_angle);
model << cos(angle), -sin(angle), 0, 0,
sin(angle), cos(angle), 0, 0,
0, 0, 1, 0,
0, 0, 0, 1;
return model;
}
投影变换
先将透视投影变成正交投影，再构件正交投影的矩阵。
Eigen::Matrix4f get_projection_matrix(float eye_fov, float aspect_ratio,
float zNear, float zFar)
{
// Students will implement this function
Eigen::Matrix4f projection = Eigen::Matrix4f::Identity();
// TODO: Implement this function
// Create the projection matrix for the given parameters.
// Then return it.
Eigen::Matrix4f persp2ortho = Eigen::Matrix4f::Identity();
persp2ortho << zNear, 0, 0, 0,
0, zNear, 0, 0,
0, 0, zNear + zFar, -zNear * zFar,
0, 0, 1, 0;
auto t = sin(aspect_ratio / 2) * zNear;
auto b = -t;
auto r = t * aspect_ratio;
auto l = -r;
Eigen::Matrix4f orthoProjection = Eigen::Matrix4f::Identity();
orthoProjection << 2 / (r - l), 0, 0, 0,
0, 2 / (t - b), 0, 0,
0, 0, 2 / (zNear - zFar), 0,
0, 0, 0, 1;
projection = orthoProjection * persp2ortho;
return projection;
}
